To act or think one is better or more important than they really are

अपनी वास्तविक स्थिति से अधिक महत्वपूर्ण या बेहतर समझना

English Usage: After his promotion, John started to be too big for his boots, ordering everyone around.

Hindi Usage: प्रमोशन के बाद, जॉन घमंड करने लगा और सबको हुक्म करने लगा।